Heretofore, heat exchangers have been assembled one unit at a time. In other words, as a single unit, straight tubes are inserted through the end plates and fin pack, and expanded to obtain a tight bond with the fins. Bent end segments and lead tubes are then secured to the ends of the tubes in any suitable manner so as to produce a leak-proof assembly.
As the unit progresses through the assembly steps, substantial handling is involved, enhancing the possibility of damage to any exposed fin surfaces. Such damaged fins must be straightened before shipping. Beyond that, further damage is possible during and after shipment.